The present specification concerns developments and improvements based on the present applicant's prior U.S. Pat. No. 3,758,150 and pending application Ser. No. 17704 filed Mar. 5, 1979 and which corresponds to Australian Patent Application No. 41119/79 laid open to public inspection in Australia Sept. 15, 1979. The wheelchair of U.S. Pat. No. 3,758,150 represented a significant development in the art in permitting a relatively lightweight and durable wheelchair to be provided yet with improved compactness when folded. The side frames of the wheelchair when adapted to be spaced apart by toggle braces in the bottom, rear and top regions. However, it was subsequently realized by the inventor that further improvements could be made particularly with a view to providing the user such as the handicapped person with a more convenient, safe and easily folded wheelchair. The disclosure of co-pending application No. 17704 relates to improvements which are considered to provide an effective solution to the problems of compactness, lightweight, durability and ease of operation by a handicapped person. In particular folding of a bottom toggle brace initiated a folding action. However, it was considered desirable to seek yet further improvements and developments with a view to reducing manufacturing costs, maintaining lightness and durability and providing a structure which could be used in a motorized wheelchair.